The Rohirrim of Walstow have attemped to hold back the forces of Mordor pouring through the barricaded East Wall, but they have seen several Orc riders slip through their defences.
You have encountered mounted riders out of the East Wall while aiding Walstow in rebuilding their defences. You should defeat as many mounted riders as you can to prevent any enemy force from regaining a foothold in the Sutcrofts.
Orc Warg-riders can be found near the stream to the north-west of Walstow and along the sides of the road west to Snowbourn.
You have defeated the mounted riders and beaten back the renewed assault from the East Wall.